I'm using the program called TMPGEnc to convert avi files to mpeg
files and have a couple of questions about the settings.

One, I'm given a choice of two stream types: ES and System.  Not sure
what the difference is.

Also, I'm given a choice for aspect ratio; i've been accepting teh
default of 1:1 VGA.  Does it matter?

Thanks.

Hi skip9801,

1-) With TMPGEnc the 2 stream types are defined as follows:

ES stands for elementary streams.
This means that the video and audio are separate files when outputted.
If you choose ES(video+audio) you will get 1 video file and 1 audio
file.

When you choose System you will get both these merged into a single
file. In most cases you want to stick with System (audio+video),
although some users have troubleshooting some problems by outputting
to separate streams, then multiplexing them using another program.

2-) Here are the recommended settings for the aspect ration depending
on the size of the source video:

video size         aspect ratio setting
320x240                 1:1 (VGA) 
352x240 (Video-CD)      4:3 NTSC 
640x480                 1:1 (VGA) 
720x480 (DV, DVD)       4:3 NTSC 
None of the above       Try 1:1 (VGA) first. 

Here is a page with the TMPGEnc settings explained:

TMPGEnc Explained V2.0.1
http://www.dvdrhelp.com/tmpgencexplained.htm

Quoting:
"Aspect Ratio: This is the aspect ratio that the final product will come out as.


1:1 VGA: This would be the correct aspect ratio if you plan to watch
your video on your computer.
4:3 525 line NTSC: This would be the ratio you would use if you want
to format your video to play on a NTSC TV (US and Japan systems).
4:3 625 line PAL: This would be the ratio you would use if you want to
format your video to play on a PAL TV (Everywhere else in the world).
16:9 line 525 NTSC: This would be the aspect ratio you would use when
you want to have your video fit properly on a 16:9 NTSC television or
to have you standalone player fix the aspect ratio for you.
16:9 line 525 PAL : This would be the aspect ratio you would use when
you want to have your video fit properly on a 16:9 PAL television or
to have you standalone player fix the aspect ratio for you."


I hope this helps, if you need any more help or clarifications please
do not hesitate to ask.

Thanks.
endo

Very detailed answer.

Glad to have been of assistance.
Thank you for the great rating.
Regards,
endo